The Shape and Figure Rotation of the Dark Halo of NGC 2915

1999 ◽  
Vol 118 (5) ◽  
pp. 2158-2171 ◽  
Author(s):  
M. Bureau ◽  
K. C. Freeman ◽  
D. W. Pfitzner ◽  
G. R. Meurer
Keyword(s):  
Dark Halo ◽  
Figure Rotation

scholarly journals Resolving the Disk-Halo Degeneracy using Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 284-287
Author(s):  
S. Aniyan ◽  
K. C. Freeman ◽  
M. Arnaboldi ◽  
O. Gerhard ◽  
L. Coccato ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Velocity Dispersion ◽  
Mass Density ◽  
Planetary Nebulae ◽  
Disk Surface ◽  
Scale Height ◽  
Dark Halo ◽  
Surface Mass ◽  
Star Forming ◽  
Light Spectra

AbstractThe decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σz) of stars in the disk and its scale height (hz), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: star-forming spirals have an old (kinematically hot) disk population and a young cold disk population. Both of these populations contribute to the integrated light spectra from which σz is measured. The measured scale height hz is for the old disk population. In the Jeans equation, σz and hz must pertain to the same population. We have developed techniques to extract the velocity dispersion of the old disk from integrated light spectra and from samples of planetary nebulae. We present the analysis of the disk kinematics of the galaxy NGC 628 using IFU data in the inner regions and planetary nebulae as tracers in the outer regions of the disk. We demonstrate that using the scale height of the old thin disk with the vertical velocity dispersion of the same population, traced by PNe, results in a maximal disk for NGC 628. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for NGC 628 appear like a submaximal disk.

Halo-independent analysis of direct dark matter detection through electron scattering

2021 ◽  
Vol 2021 (12) ◽  
pp. 048
Author(s):  
Muping Chen ◽  
Graciela B. Gelmini ◽  
Volodymyr Takhistov
Keyword(s):  
Dark Matter ◽  
Direct Detection ◽  
Dark Matter Halo ◽  
Dark Halo ◽  
Sufficient Energy ◽  
Independent Analysis ◽  
Dark Matter Detection ◽  
Dark Matter Scattering ◽  
Matter Detection ◽  
Direct Dark Matter

Abstract Sub-GeV mass dark matter particles whose collisions with nuclei would not deposit sufficient energy to be detected, could instead be revealed through their interaction with electrons. Analyses of data from direct detection experiments usually require assuming a local dark matter halo velocity distribution. In the halo-independent analysis method, properties of this distribution are instead inferred from direct dark matter detection data, which allows then to compare different data without making any assumption on the uncertain local dark halo characteristics. This method has so far been developed for and applied to dark matter scattering off nuclei. Here we demonstrate how this analysis can be applied to scattering off electrons.

Galactic Spiral Pattern beyond the Optical Size Induced by the Triaxial Dark Halo

2015 ◽  
Vol 24 (2) ◽  
Author(s):  
M. Butenko ◽  
A. Khoperskov ◽  
S. Khoperskov
Keyword(s):  
Dark Halo ◽  
Spiral Pattern ◽  
Spiral Structures ◽  
Galactic Spiral

AbstractWe suggest a possible mechanism for the formation of non-tidal gaseous structures in galactic outskirts. According to recent observations, extended spiral structures are detected beyond the optical radii

scholarly journals Estimate of dark halo ellipticity by lensing flexion

2011 ◽  
Vol 528 ◽  
pp. A52 ◽  
Author(s):  
X. Er ◽  
P. Schneider
Keyword(s):  
Dark Halo

scholarly journals Excursion set peaks: a self-consistent model of dark halo abundances and clustering

2013 ◽  
Vol 431 (2) ◽  
pp. 1503-1512 ◽  
Author(s):  
Aseem Paranjape ◽  
Ravi K. Sheth ◽  
Vincent Desjacques
Keyword(s):  
Dark Halo ◽  
Consistent Model ◽  
Self Consistent ◽  
Excursion Set

scholarly journals The insight into the dark side – I. The pitfalls of the dark halo parameters estimation

2016 ◽  
Vol 463 (3) ◽  
pp. 2523-2541 ◽  
Author(s):  
Anna S. Saburova ◽  
Anastasia V. Kasparova ◽  
Ivan Yu. Katkov
Keyword(s):  
Parameters Estimation ◽  
Dark Side ◽  
Dark Halo ◽  
Insight Into

scholarly journals Galactic Kinematics on the Basis of Modern Proper Motion Data

1995 ◽  
Vol 166 ◽  
pp. 217-226
Author(s):  
M. Miyamoto
Keyword(s):  
High Precision ◽  
Proper Motion ◽  
Galactic Kinematics ◽  
Dark Halo ◽  
Motion Data ◽  
Structure And Dynamics ◽  
The Galaxy ◽  
Galactic Astronomy ◽  
Astrometric Data

An accumulation of high precision astrometric data in conjunction with high-precision monitoring of the Earth's orientation, motivates “Galactic Astronomy”. As regards local kinematics, all of the three components of both the vorticity and the shear of stars can be completely determined, in addition to the velocity ellipsoid. We can now be released from the constraint of the “axisymmetric” galaxy. The determination of the proper motion of the LMC will be crucial to understanding the global structure and dynamics of the Galaxy with the dark halo and MACHO's motions.

scholarly journals First Gaia dynamical model of the Milky Way disc with six phase space coordinates: a test for galaxy dynamics

2020 ◽  
Vol 494 (4) ◽  
pp. 6001-6011 ◽  
Author(s):  
Maria Selina Nitschai ◽  
Michele Cappellari ◽  
Nadine Neumayer
Keyword(s):  
Phase Space ◽  
Milky Way ◽  
Dynamical Model ◽  
Total Density ◽  
Dark Halo ◽  
Stellar Kinematics ◽  
Galaxy Dynamics ◽  
Dispersion Tensor ◽  
External Galaxies ◽  
Solar Position

ABSTRACT We construct the first comprehensive dynamical model for the high-quality subset of stellar kinematics of the Milky Way disc, with full 6D phase-space coordinates, provided by the Gaia Data Release 2. We adopt an axisymmetric approximation and use an updated Jeans Anisotropic Modelling (JAM) method, which allows for a generic shape and radial orientation of the velocity ellipsoid, as indicated by the Gaia data, to fit the mean velocities and all three components of the intrinsic velocity dispersion tensor. The Milky Way is the first galaxy for which all intrinsic phase space coordinates are available, and the kinematics are superior to the best integral-field kinematics of external galaxies. This situation removes the long-standing dynamical degeneracies and makes this the first dynamical model highly overconstrained by the kinematics. For these reasons, our ability to fit the data provides a fundamental test for both galaxy dynamics and the mass distribution in the Milky Way disc. We tightly constrain the volume average total density logarithmic slope, in the radial range 3.6–12 kpc, to be αtot = −2.149 ± 0.055 and find that the dark halo slope must be significantly steeper than αDM = −1 (NFW). The dark halo shape is close to spherical and its density is ρDM(R⊙) = 0.0115 ± 0.0020 M⊙ pc−3 (0.437 ± 0.076 GeV cm−3), in agreement with previous estimates. The circular velocity at the solar position vcirc(R⊙) = 236.5 ± 3.1 km s−1 (including systematics) and its gently declining radial trends are also consistent with recent determinations.

scholarly journals The Disk and Dark Halo Mass of the Barred Galaxy NGC 4123. II. Fluid‐Dynamical Models

2001 ◽  
Vol 546 (2) ◽  
pp. 931-951 ◽  
Author(s):  
Benjamin J. Weiner ◽  
J. A. Sellwood ◽  
T. B. Williams
Keyword(s):  
Dark Halo ◽  
Dynamical Models
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